In a typical card modular platform, a plurality of boards are installed in a shelf having a backplane to which each board is communicatively coupled. For example, FIG. 1 shows a shelf 100 having an integrated subrack 102 including a plurality of slots into which respective boards 104 are installed. At the rear end of the integrated subrack 102 is a backplane 106. The backplane enables inter-board communication via a well-known communication scheme, such as Ethernet, Fibre Channel, PCI ExpressAS, etc. The communication links may also be TDM (Time Division Multiplexed) fabrics, such as Sonet/SDH or buses such as PCI. Under any of these schemes, each board is identified by a unique slot address.
In addition, boards may have common IP addresses in certain configurations. For example, if there is an active and standard by board, it is possible for a common IP address to follow the active board. In case of boards in multiple slots do the same function in a load sharing environment, it is possible to have a common IP address for all those boards where a switch implements load sharing using one of many load sharing algorithms. In that case, the traffic is routed through the appropriate ports to different slots.
One common approach is to employ Ethernet for inter-board communication, as illustrated in FIG. 2, which shows the internal configuration of a telecommunications (telco) switch 200. Switch 200 includes a dual star Ethernet fabric configured with a pair of switch fabrics 202A and 202B, each of which is coupled in communication to a plurality of boards 204A-G via a common backplane (not shown). The two switch fabrics 202A and 202B route traffic between any two boards, while the dual star configuration provides 1+1 redundancy. Switch fabrics 202A and 202B are also coupled in communication with a redundant external core switch 206, which provides an interface to an external network 208.
In general, telco equipment and the like need to provide 24-7 availability, thus the use of redundancy in the switch fabric and external core switch. At the same time, each slot within a given shelf will be configured for a particular function. Once configured, the configuration remains the same unless a major event warrants reconfiguration. Redundant boards may be used to provide non-stop service. In case of a failure, automatic fail-over to the standby board takes place and the failed board is eventually replaced. This sequence ensures that the operation is not interrupted.
Among the configuration operations is the assignment of an IP address for each of a board's Ethernet ports. In a typical installation, each slot within a shelf may be configured for a particular function, with the possibility of multiple slots used to perform the same function in a load sharing manner. It is possible that boards in certain slots are loaded with pre-configured set of software, including operating systems, drivers, applications, configuration settings, etc. Furthermore, at least a portion of the boards, such as the system manager board/s, is aware of the functions served by the other boards. Accordingly, it is advantageous to assign an IP address for a replacement board that matches the IP address of the board being replaced. Under this consideration, each board is assigned a static IP address, as illustrated by IP addresses 210, as illustrated in FIG. 2. Also it is advantageous to load software images dependent on slot address since as described earlier each slot is pre-assigned a particular function. This allows for ease of deployment in a modular platform environment by avoiding manual intervention, potential human errors and saving time.
There are several conventional methods for assigning static IP addresses. On method is to manually configure the board with a pre-assigned address. This is time consuming and error prone. It also requires the board to be up and running prior to assigning an address. Another scheme is to employ a DHCP (Dynamic Host Configuration Protocol) server, which is normally used to dynamically assign addresses. However, in this instance, it is desired to assign the new replacement board a pre-determined address. DHCP supports this option via an address reservation mechanism. The mechanism works by knowing the MAC (media access channel) address of the board's network port. The MAC address is entered into a DHCP console or the like, along with the pre-assigned address. When the board is installed, a DHCP message exchange occurs during which the board identifies its MAC address and the DHCP server issues the corresponding pre-assigned address. In a somewhat similar manner, IP addresses may be assigned by an Ethernet switch.
While the foregoing DHCP scheme works for assigning static IP addresses, it has its limitations. For example, a critical requirement for all networks is each node must have a unique network address. Most, if not all, DHCP server configuration schemes do not let the same IP address be reserved for more than one MAC address, and thus one board. As a result, it is not possible to configure IP addresses for replacement boards in advance using a conventional DHCP reservation. It is also more complex to access the DHCP server configuration and make changes as the access to it is limited and could consume more time. Besides, the administrator who replaces the board may not have access privileges to make changes to network configurations.